Two phrases that Daniel Patrick Moynihan put into America’s political lexicon two decades ago are increasingly pertinent. They explain the insufficient dismay about recent economic numbers.

Moynihan said that when deviant behaviors — e.g., violent crime, or births to unmarried women — reach a certain level, society soothes itself by “defining deviancy down.” It de-stigmatizes the behaviors by declaring them normal.

And sometimes, Moynihan said, social problems are the result of “iatrogenic government.” In medicine, an iatrogenic ailment is inadvertently induced by a physician or medicine; in social policy, iatrogenic problems are caused by government.

When the economy grew by just 2.6 percent in 2014’s fourth quarter, The New York Times headline cheerfully said, “Economy Pulls Ahead.”

The story said the US economy is “an island of relative strength” in a world facing “renewed torpor and turmoil.” This was defining failure down.

The Wall Street Journal said, “US Economy Hits Speed Bumps,” as if speedy growth had been normal for a while.

The speeding consisted of one quarter (2014’s third) of 5 percent growth. But we had gone 43 consecutive quarters without 5 percent growth, the longest such period since at least 1947.

Even with this third quarter, growth for 2014 was just 2.4 percent, making this the ninth straight year under 3 percent. The recovery from the recession of 1981-82 included five quarters of 7 percent or higher growth, and five years averaged 4.6 percent growth.

And November’s job growth of 353,000 was just the fifth month of 300,000-plus growth in the 68 months since the sluggish recovery began in June 2009.

The 1960s saw nine months of 300,000-plus job creation — and the nation’s population in 1969 was nearly 118 million smaller than today’s. The ’80s had 23 months of 300,000-plus jobs, and the population in 1989 was 73 million smaller than today’s 320 million.

Nicole Gelinas writes in City Journal: “A healthy economy should add 200,000 new jobs every month, even when it’s not recovering from a recession. By that standard, America should have 133 million people working in the private sector right now, not 118.4 million.”

Economic weakness (new busi­ness formations are at a 35-year low) is both a cause and a consequence of alarming cultural changes.

In 1960, 12 percent of 25- to-34-year-olds were never married; today, 49 percent. Although the population was 27 million larger in 2010 than in 2000, there were fewer births in 2010.

To a considerable extent, the lingering economic anemia is an iatrogenic social ailment, induced by government behavior.

The business burdens and uncertainties created by the Affordable Care Act are just part of the Obama administration’s regulatory mania (3,659 new regulations finalized in 2013 and another 2,594 proposed, notes Wayne Crews of the Competitive Enterprise Institute).

Obama’s plan to tax the earnings from parents’ “529” college savings plans lived just long enough to indicate why some progressives perhaps prefer slow economic growth.

Rapid growth reduces the appeal of redistributive policies and the need for the bitter, divisive politics that advance such policies. The 529s help families achieve self-sufficiency.

This excites progressives’ dislike of any private provision that impedes implementation of their dependency agenda.

The progressive project of maximizing the number of people dependent on government is also aided by the acid of insecurity that grows rapidly when the economy does not.

Anxious and disappointed people are susceptible to progressives’ blandishments about the political allocation of wealth and opportunity — “free” this and that.

By making slow growth normal, iatrogenic government serves the progressive program of defining economic failure down.